The Marmara, Turkey Earthquake of August 17, 1999: Reconnaissance Report

The August 17, 1999 Mw 7.4 Marmara earthquake is a devastating catastrophe and great
human tragedy for the Turkish people. Approximately 17,000 fatalities and 44,000 injuries
occurred, with an estimated 20,000 collapsed buildings displacing more than 250,000
people, making it one of the worst natural disasters in recent decades.

The affected region around Izmit Bay is heavily industrialized and accounts for perhaps
10% of Turkeys GDP. Combined with other economic problems, the earthquake is
expected to be a severe burden on the national economy, reducing national GNP by 0.6~1.0 %
(World Bank, 1999).

The earthquake should have come as no surprise, since the long history of earthquakes
is well-known (Ambraseys and Finkel, 1995), Table 1-1. Additional evidence for this
events potential was the clear pattern of sequential segmented rupturing of the
North Anatolian Fault Zone (NAFZ) as pointed out by Toksöz et al. in 1979 and Stein et
al. in 1997, (discussed by Papageorgiou in Section 2).

The approximately 125 km of fault rupture on the North Anatolian Fault Zone is clearly
analogous to situations in other parts of the world, most notably with the San Andreas
fault in the San Francisco Bay Area of California. The strong ground shaking due to this
fault rupture, combined with soft soils around the perimeter of Izmit Bay and other areas
(e.g., Adapazari), resulted in significant geotechnical effects and permanent ground
deformations (discussed by Mitchell and Holzer in Section 3). These geotechnical effects
were consistent with those associated with other recent major earthquakes, and resulted in
streets and buildings on the bayshore being submerged 1~2 meters in this event, and
Adapazaris water distribution system being virtually destroyed.

However, the most dramatic damage and greatest contributor to the disaster was the
widespread collapse of numerous multi-story reinforced concrete apartment blocks. Almost
the only building type in the region is non-ductile reinforced concrete frames with hollow
clay tile infill which, combined with soft stories, results in a pancake type
of collapse (discussed by Bruneau in Section 4). Requirements for proper
earthquake-resistive construction exist in the Turkish building code, which is a very
modern code. Why werent these requirements adhered to? One important factor has been
the rapid development of Turkey in general, and particularly the Marmara region. From 1990
to 1997 for example, the province of Kocaelis population grew 26%. Rapid development
of the Marmara region overwhelmed local governments ability to monitor construction,
and led to unregulated building, resulting in inadequate lateral force systems in
buildings.

This lesson is further emphasized by the performance of structures designed and
constructed by more centralized organizations with access to modern engineering, such as
the transportation systems (discussed by Mander in Section 5), industrial facilities
(discussed by Johnson in Section 6) and lifelines (Section 7). In these cases, relatively
little damage occurred, and the major motorways, water treatment and transmission systems,
gas systems, and national power grid, were all functional within hours of the earthquake.
Industrial facility performance was more mixed, with some dramatic damage, such as at the
Tüpras refinery (site of a major fire), but many facilities performed very well.

The human dimensions of the August 17 earthquake continued for many days, as Turks and
rescuers from around the world struggled to find and save those trapped in the literally
thousands of collapsed buildings. This task, which re-played similar efforts seen in
Mexico City in 1985, Armenia in 1988 and elsewhere, is simply overwhelming. As Mitchell
discusses in Section 8, the organization and technology does not currently exist to
perform this task with any real effectiveness, so that prevention of the problem, via
effective retrofitting, is the solution. The cost of disasters is further increased by the
resources that must be devoted to tent cities and more durable temporary housing, debris
removal and other necessary tasks, as discussed by Webb in Section 9. Both sections 8 and
9 also offer excellent insights into the social and political ramifications of such a
trauma to the social fabric.

Very interesting in this earthquake was the application of new technologies for rapidly
assessing and reacting to the disaster, in near real-time. Remote sensing,
GPS, GIS and emergency decision support systems offer the promise of efficiently employing
available resources in a timely manner, thus in the future, potentially saving those who
are currently lost. Eguchi and co-workers in the final chapter discuss current efforts at
applying and understanding these technologies, which are an extremely promising area for
further research.

In a sense, the August 17 Marmara earthquake was a narrow-banded event.
That is, considering the entire spectrum of the built environment, the damage resulting
from the event, while substantial, was generally within the resources of Turkey to manage
and even tolerate, with one exception. The exception was the dismal performance of the
reinforced concrete frames, virtually ubiquitous in the region. The collapse of thousands
of these buildings transformed this earthquake from a damaging event to a catastrophe.
Within the spectrum of the built environment, only this aspect was a spike.
Design and construction of reinforced concrete frames to withstand strong earthquake
motions is possible, and the principles are well understood by Turkish engineers.
Unfortunately, the rapid development of the region overtaxed the ability of the society to
assure that these principles were followed. The result was inadequate buildings, when
there need not have been, and a tragic catastrophe. The ultimate lesson therefore is that
building and development is simply not a physical process - governmental institutions and
social processes must develop in parallel, to keep up with the physical demands and assure
minimum acceptable standards of construction and public safety. The alternative is seen in
Figure 1-1, thousands forced to stand by, while victims die in the rubble.

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